Systems and methods for selecting low-power, effective signal delivery parameters for an implanted pulse generator

ABSTRACT

Systems and methods for selecting low-power, effective signal delivery parameters for an implanted pulse generator are disclosed. A representative system includes a signal generator and a computer-readable medium that, for first and second signals, increases and decreases an amplitude of the signal over multiple steps from a baseline amplitude at which the patient has a baseline response. At individual step increases and decreases, the system receives a pain score based on the patient&#39;s response. The instructions compare the pain scores for the two signals and determine one of the signals for additional therapy to the patient, based on the pain scores and an expected energy consumption of the signals.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 15/057,913, filed Mar. 1, 2016, which is a continuation of U.S.patent application Ser. No. 14/657,971, filed Mar. 13, 2015, which areincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure is directed to systems and methods for selectinglow-power, effective signal delivery parameters for an implanted pulsegenerator. In particular applications, the techniques disclosed hereinare applied in the context of delivering high-frequency,paresthesia-free therapy signals.

BACKGROUND

Neurological stimulators have been developed to treat pain, movementdisorders, functional disorders, spasticity, cancer, cardiac disorders,and various other medical conditions. Implantable neurologicalstimulation systems generally have an implantable signal generator andone or more leads that deliver electrical pulses to neurological tissueor muscle tissue. For example, several neurological stimulation systemsfor spinal cord stimulation (SCS) have cylindrical leads that include alead body with a circular cross-sectional shape and one or moreconductive rings (i.e., contacts) spaced apart from each other at thedistal end of the lead body. The conductive rings operate as individualelectrodes and, in many cases, the SCS leads are implantedpercutaneously through a needle inserted into the epidural space, withor without the assistance of a stylet.

Once implanted, the signal generator applies electrical pulses to theelectrodes, which in turn modify the function of the patient's nervoussystem, such as by altering the patient's responsiveness to sensorystimuli and/or altering the patient's motor-circuit output. In SCStherapy for the treatment of pain, the signal generator applieselectrical pulses to the spinal cord via the electrodes. In conventionalSCS therapy, electrical pulses are used to generate sensations (known asparesthesia) that mask or otherwise alter the patient's sensation ofpain. For example, in many cases, patients report paresthesia as atingling sensation that is perceived as less uncomfortable than theunderlying pain sensation.

In contrast to traditional or conventional (i.e., paresthesia-based)SCS, a form of paresthesia-free SCS has been developed that uses therapysignal parameters that treat the patient's sensation of pain withoutgenerating paresthesia or otherwise using paresthesia to mask thepatient's sensation of pain. One of several advantages ofparesthesia-free SCS therapy systems is that they eliminate the need foruncomfortable paresthesias, which many patients find objectionable.However, a challenge with paresthesia-free SCS therapy systems is thatthe signal may be delivered at frequencies, amplitudes, and/or pulsewidths that use more power than conventional SCS systems. As a result,there is a need to develop optimized systems and methods for effectivelydelivering therapy while efficiently using power resources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a partially schematic illustration of an implantable spinalcord modulation system positioned at the spine to deliver therapeuticsignals in accordance with several embodiments in the presenttechnology.

FIG. 1B is a partially schematic, cross-sectional illustration of apatient's spine, illustrating representative locations for implantedlead bodies in accordance with embodiments of the present technology.

FIG. 2 is a flow diagram illustrating a process for selecting signaldelivery parameters in accordance with an embodiment of the presenttechnology.

FIG. 3 is a flow diagram illustrating a representative process forselecting signal delivery parameters in accordance with anotherembodiment of the present technology.

DETAILED DESCRIPTION

General aspects of the environments in which the disclosed technologyoperates are described below under Heading 1.0 (“Overview”) withreference to FIGS. 1A and 1B. Particular embodiments of the technologyare described further under Heading 2.0 (“Representative Embodiments”)with reference to FIGS. 2 and 3. Additional embodiments are describedunder Heading 3.0 (“Additional Embodiments”).

1.0 OVERVIEW

One example of a paresthesia-free SCS therapy system is a “highfrequency” SCS system. High frequency SCS systems can inhibit, reduce,and/or eliminate pain via waveforms with high frequency elements orcomponents (e.g., portions having high fundamental frequencies),generally with reduced or eliminated side effects. Such side effects caninclude unwanted paresthesia, unwanted motor stimulation or blocking,unwanted pain or discomfort, and/or interference with sensory functionsother than the targeted pain. In a representative embodiment, a patientmay receive high frequency therapeutic signals with at least a portionof the therapy signal at a frequency of from about 1.5 kHz to about 100kHz, or from about 1.5 kHz to about 50 kHz, or from about 3 kHz to about20 kHz, or from about 5 kHz to about 15 kHz, or at frequencies of about8 kHz, 9 kHz, or 10 kHz. These frequencies are significantly higher thanthe frequencies associated with conventional “low frequency” SCS, whichare generally below 1,200 Hz, and more commonly below 100 Hz.Accordingly, modulation at these and other representative frequencies(e.g., from about 1.5 kHz to about 100 kHz) is occasionally referred toherein as “high frequency stimulation,” “high frequency SCS,” and/or“high frequency modulation.” Further examples of paresthesia-free SCSsystems are described in U.S. Patent Publication Nos. 2009/0204173 and2010/0274314, the respective disclosures of which are hereinincorporated by reference in their entireties.

FIG. 1A schematically illustrates a representative patient therapysystem 100 for providing relief from chronic pain and/or otherconditions, arranged relative to the general anatomy of a patient'sspinal column 191. The system 100 can include a signal generator 101(e.g., an implanted or implantable pulse generator or IPG), which may beimplanted subcutaneously within a patient 190 and coupled to one or moresignal delivery elements or devices 110. The signal delivery elements ordevices 110 may be implanted within the patient 190, typically at ornear the patient's spinal cord midline 189. The signal delivery elements110 carry features for delivering therapy to the patient 190 afterimplantation. As shown, the signal generator 101 can be implanted withinthe patient. In such an embodiment, the signal generator 101 can beconnected directly to the signal delivery devices 110, or it can becoupled to the signal delivery devices 110 via a signal link or leadextension 102. In an embodiment wherein the signal generator is externalto the patient, the signal generator can deliver a signal to the signaldelivery device 110 via a wireless link, such as RF communication. In afurther representative embodiment, the signal delivery devices 110 caninclude one or more elongated lead(s) or lead body or bodies 111(identified individually as a first lead 111 a and a second lead 111 b).As used herein, the terms signal delivery device, lead, and/or lead bodyinclude any of a number of suitable substrates and/or support membersthat carry electrodes/devices for providing therapy signals to thepatient 190. For example, the lead or leads 111 can include one or moreelectrodes or electrical contacts that direct electrical signals intothe patient's tissue, e.g., to provide for therapeutic relief. In otherembodiments, the signal delivery elements 110 can include structuresother than a lead body (e.g., a paddle) that also direct electricalsignals and/or other types of signals to the patient 190.

In a representative embodiment, one signal delivery device may beimplanted on one side of the spinal cord midline 189, and a secondsignal delivery device may be implanted on the other side of the spinalcord midline 189. For example, the first and second leads 111 a, 111 bshown in FIG. 1A may be positioned just off the spinal cord midline 189(e.g., about 1 mm offset) in opposing lateral directions so that the twoleads 111 a, 111 b are spaced apart from each other by about 2 mm. Inparticular embodiments, the leads 111 may be implanted at a vertebrallevel ranging from, for example, about T8 to about T12. In otherembodiments, one or more signal delivery devices can be implanted atother vertebral levels, e.g., as disclosed in U.S. Patent ApplicationPublication No. 2013/0066411, which is incorporated herein by referencein its entirety.

The signal generator 101 can transmit signals (e.g., electrical signals)to the signal delivery elements 110 that up-regulate (e.g., excite)and/or down-regulate (e.g., block or suppress) target nerves. As usedherein, and unless otherwise noted, the terms “modulate,” “modulation,”“stimulate,” and “stimulation” refer generally to signals that haveeither type of the foregoing effects on the target nerves. The signalgenerator 101 can include a machine-readable (e.g., computer-readable)or controller-readable medium containing instructions for generating andtransmitting suitable therapy signals. The signal generator 101 and/orother elements of the system 100 can include one or more processor(s)107, memory unit(s) 108, and/or input/output device(s) 112. Accordingly,the process of providing modulation signals, providing guidanceinformation for positioning the signal delivery devices 110,establishing battery charging and/or discharging parameters,establishing signal delivery parameters, and/or executing otherassociated functions can be performed by computer-executableinstructions contained by, on or in computer-readable media located atthe pulse generator 101 and/or other system components. Further, thepulse generator 101 and/or other system components may include dedicatedhardware, firmware, and/or software for executing computer-executableinstructions that, when executed, perform any one or more methods,processes, and/or sub-processes described herein; e.g., the methods,processes, and/or sub-processes described with reference to FIGS. 2-3below. The dedicated hardware, firmware, and/or software also serve as“means for” performing the methods, processes, and/or sub-processesdescribed herein. The signal generator 101 can also include multipleportions, elements, and/or subsystems (e.g., for directing signals inaccordance with multiple signal delivery parameters), carried in asingle housing, as shown in FIG. 1A, or in multiple housings.

The signal generator 101 can also receive and respond to an input signalreceived from one or more sources. The input signals can direct orinfluence the manner in which the therapy, charging, parameter selectionand/or other process instructions are selected, executed, updated,and/or otherwise performed. The input signals can be received from oneor more sensors (e.g., an input device 112 shown schematically in FIG.1A for purposes of illustration) that are carried by the signalgenerator 101 and/or distributed outside the signal generator 101 (e.g.,at other patient locations) while still communicating with the signalgenerator 101. The sensors and/or other input devices 112 can provideinputs that depend on or reflect patient state (e.g., patient position,patient posture, and/or patient activity level), and/or inputs that arepatient-independent (e.g., time). Still further details are included inU.S. Pat. No. 8,355,797, incorporated herein by reference in itsentirety.

In some embodiments, the signal generator 101 and/or signal deliverydevices 110 can obtain power to generate the therapy signals from anexternal power source 103. In one embodiment, for example, the externalpower source 103 can by-pass an implanted signal generator and generatea therapy signal directly at the signal delivery devices 110 (or viasignal relay components). The external power source 103 can transmitpower to the implanted signal generator 101 and/or directly to thesignal delivery devices 110 using electromagnetic induction (e.g., RFsignals). For example, the external power source 103 can include anexternal coil 104 that communicates with a corresponding internal coil(not shown) within the implantable signal generator 101, signal deliverydevices 110, and/or a power relay component (not shown). The externalpower source 103 can be portable for ease of use.

In another embodiment, the signal generator 101 can obtain the power togenerate therapy signals from an internal power source, in addition toor in lieu of the external power source 103. For example, the implantedsignal generator 101 can include a non-rechargeable battery or arechargeable battery to provide such power. When the internal powersource includes a rechargeable battery, the external power source 103can be used to recharge the battery. The external power source 103 canin turn be recharged from a suitable power source (e.g., conventionalwall power).

During at least some procedures, an external stimulator or trialmodulator 105 can be coupled to the signal delivery elements 110 duringan initial procedure, prior to implanting the signal generator 101. Forexample, a practitioner (e.g., a physician and/or a companyrepresentative) can use the trial modulator 105 to vary the modulationparameters provided to the signal delivery elements 110 in real time,and select optimal or particularly efficacious parameters. Theseparameters can include the location from which the electrical signalsare emitted, as well as the characteristics of the electrical signalsprovided to the signal delivery devices 110. In some embodiments, inputis collected via the external stimulator or trial modulator and can beused by the clinician to help determine what parameters to vary. In atypical process, the practitioner uses a cable assembly 120 totemporarily connect the trial modulator 105 to the signal deliverydevice 110. The practitioner can test the efficacy of the signaldelivery devices 110 in an initial position. The practitioner can thendisconnect the cable assembly 120 (e.g., at a connector 122), repositionthe signal delivery devices 110, and reapply the electrical signals.This process can be performed iteratively until the practitioner obtainsthe desired position for the signal delivery devices 110. Optionally,the practitioner may move the partially implanted signal deliverydevices 110 without disconnecting the cable assembly 120. Furthermore,in some embodiments, the iterative process of repositioning the signaldelivery devices 110 and/or varying the therapy parameters may not beperformed.

The signal generator 101, the lead extension 102, the trial modulator105 and/or the connector 122 can each include a receiving element 109.Accordingly, the receiving elements 109 can be patient implantableelements, or the receiving elements 109 can be integral with an externalpatient treatment element, device or component (e.g., the trialmodulator 105 and/or the connector 122). The receiving elements 109 canbe configured to facilitate a simple coupling and decoupling procedurebetween the signal delivery devices 110, the lead extension 102, thepulse generator 101, the trial modulator 105 and/or the connector 122.The receiving elements 109 can be at least generally similar instructure and function to those described in U.S. Patent ApplicationPublication No. 2011/0071593, incorporated by reference herein in itsentirety.

After the signal delivery elements 110 are implanted, the patient 190can receive therapy via signals generated by the trial modulator 105,generally for a limited period of time. During this time, the patientwears the cable assembly 120 and the trial modulator 105 outside thebody. Assuming the trial therapy is effective or shows the promise ofbeing effective, the practitioner then replaces the trial modulator 105with the implanted signal generator 101, and programs the signalgenerator 101 with therapy programs selected based on the experiencegained during the trial period. Optionally, the practitioner can alsoreplace the signal delivery elements 110. Once the implantable signalgenerator 101 has been positioned within the patient 190, the therapyprograms provided by the signal generator 101 can still be updatedremotely via a wireless physician's programmer (e.g., a physician'slaptop, a physician's remote or remote device, etc.) 117 and/or awireless patient programmer 106 (e.g., a patient's laptop, patient'sremote or remote device, etc.). Generally, the patient 190 has controlover fewer parameters than does the practitioner. For example, thecapability of the patient programmer 106 may be limited to startingand/or stopping the signal generator 101, and/or adjusting the signalamplitude. The patient programmer 106 may be configured to accept painrelief input as well as other variables, such as medication use.

In any of the foregoing embodiments, the parameters in accordance withwhich the signal generator 101 provides signals can be adjusted duringportions of the therapy regimen. For example, the frequency, amplitude,pulse width, and/or signal delivery location can be adjusted inaccordance with a pre-set therapy program, patient and/or physicianinputs, and/or in a random or pseudorandom manner. Such parametervariations can be used to address a number of potential clinicalsituations. Certain aspects of the foregoing systems and methods may besimplified or eliminated in particular embodiments of the presentdisclosure. Further aspects of these and other expected beneficialresults are detailed in U.S. Patent Application Publication Nos.2010/0274314; 2009/0204173; and 2013/0066411 (all previouslyincorporated by reference) and U.S. Patent Application Publication No.2010/0274317, which is incorporated herein by reference in its entirety.

FIG. 1B is a cross-sectional illustration of the spinal cord 191 and anadjacent vertebra 195 (based generally on information from Crossman andNeary, “Neuroanatomy,” 1995 (published by Churchill Livingstone)), alongwith multiple leads 111 (shown as leads 111 a-111 e) implanted atrepresentative locations. For purposes of illustration, multiple leads111 are shown in FIG. 1B implanted in a single patient. In actual use,any given patient will likely receive fewer than all the leads 111 shownin FIG. 1B.

The spinal cord 191 is situated within a vertebral foramen 188, betweena ventrally located ventral body 196 and a dorsally located transverseprocess 198 and spinous process 197. Arrows V and D identify the ventraland dorsal directions, respectively. The spinal cord 191 itself islocated within the dura mater 199, which also surrounds portions of thenerves exiting the spinal cord 191, including the ventral roots 192,dorsal roots 193 and dorsal root ganglia 194. The dorsal roots 193 enterthe spinal cord 191 at the dorsal root entry zone 187, and communicatewith dorsal horn neurons located at the dorsal horn 186. In oneembodiment, the first and second leads 111 a, 111 b are positioned justoff the spinal cord midline 189 (e.g., about 1 mm. offset) in opposinglateral directions so that the two leads 111 a, 111 b are spaced apartfrom each other by about 2 mm, as discussed above. In other embodiments,a lead or pairs of leads can be positioned at other locations, e.g.,toward the outer edge of the dorsal root entry zone 187 as shown by athird lead 111 c, or at the dorsal root ganglia 194, as shown by afourth lead 111 d, or approximately at the spinal cord midline 189, asshown by a fifth lead 111 e.

2.0 REPRESENTATIVE EMBODIMENTS

Systems of the type described above with reference to FIGS. 1A-1B caninclude implanted pulse generators (IPGs) having rechargeable batteriesor other rechargeable power sources that are periodically recharged withan external charger. In addition, such devices are configured togenerate therapy signals, typically at higher frequencies than are usedfor conventional SCS, to produce pain relief without generatingparesthesia in the patient. High frequency signals, however, may consumemore energy than low frequency signals, e.g., for a given therapy, andmay accordingly deplete the rechargeable power source more rapidly thanconventional SCS therapy signals do. As a result, the patient may berequired to recharge the implantable device more often than would berequired for a conventional SCS device. Techniques in accordance withthe present technology, described further below, can allow the system toautomatically determine signal parameters that produce effective paintreatment with reduced (e.g., minimal) energy consumption.

In particular embodiments, embodiments of the therapy disclosed hereindo not produce paresthesia or other undesirable side effects. Thischaracteristic can significantly improve the degree to which the processfor selecting the signal delivery parameters can be automated. Inparticular, with standard, conventional, low frequency SCS, thetherapeutic efficacy (e.g., the degree of pain relief) typicallyincreases with the amplitude of the signal. The power required toproduce the signal also increases with amplitude. However, as theamplitude increases, other side effects, such as motor reflex and/or anoverwhelming sensory intensity, overshadow the beneficial pain reliefresults. Accordingly, the approach for maximizing pain relief viaconventional low frequency SCS therapy is typically to increase theamplitude of the signal until the patient can no longer tolerate theside effects. This can be a time-consuming operation, because thepractitioner wishes to avoid over-stimulating the patient. It also tendsto result in a therapy signal that requires a large amount of power, dueto the high amplitude. Still further, this process is typically notautomated, so as to avoid inadvertently over-stimulating the patient asthe amplitude is increased.

By contrast, it has been discovered that the therapeutic efficacy (e.g.,level of pain relief) produced by a high frequency signal may begin todecrease at higher amplitudes, before other sensory or motorside-effects appear to limit further increases in amplitude. Because thetherapeutic efficacy level is expected to decrease before the onset ofunwanted motor or sensory effects, the presently disclosed systems andmethods can automatically increment and/or decrement the stimulationamplitude, within pre-selected ranges (e.g., efficacy ranges), withouttriggering unwanted side effects. This technique can be used to identifyan amplitude at one or more frequencies that both produces effectivetherapy, and does so at a relatively low energy consumption rate (e.g.,power). Further details are described below.

FIG. 2 is a flow diagram illustrating a representative process 200 forselecting a therapy signal for delivery to a patient in accordance withan embodiment of the present technology. Process portion 201 includesconfiguring a signal generator to deliver therapy signals at multiplecombinations of parameters. The parameters can include combinations ofamplitudes and frequencies in particular embodiments. In otherembodiments, the parameters can include other characteristics of thetherapy signal, for example, the duty cycle, pulse width, and/orinterpulse interval. In any of these embodiments, process portion 203includes determining the patient's response to individual combinations(e.g., each combination) of applied signal parameters. The patient'sresponse can be measured using any of a variety of suitable techniquesthat have been developed for identifying the patient's level of pain.Such techniques include using VAS scores, NRS scores, Likertsatisfaction scales, Oswestry disability indices, among others. Thesetechniques can be used to provide a patient-specific but quantifiablemeasure of the efficacy of the therapy, which is expected to change asthe signal delivery parameters change. The foregoing techniques includefeedback from the patient via deliberate patient participation (e.g.,the patient consciously writing, describing or keying in a pain score).In other embodiments, the patient's response may be determined withoutthis level of patient participation, e.g., by directly measuring patientphysiological values that are correlated with the patient's pain level.

Process portion 205 includes determining the expected energy consumptionfor individual combinations (e.g., each combination) of signals appliedto the patient. For example, process portion 205 can include integratingthe area under a wave form graph of amplitude as a function of time.Accordingly, signals with high amplitudes and high frequencies consumemore power than signals with low amplitudes and low frequencies.However, in particular embodiments, signals with high frequencies butlow amplitudes can consume more power than signals with low frequenciesand high amplitudes, and vice versa. The level of computation used todetermine whether a particular combination of signal delivery parametersconsumes more energy than another can vary in complexity, as will bedescribed in further detail later.

Process portion 207 includes delivering one or more therapy signals foradditional therapy based on (a) the patient's responses to the signals(i.e., the therapeutic efficacy of the signals) and (b) the expectedenergy consumption associated with the signals. The manner in whichthese two characteristics are weighted can vary from one patient toanother. For example, some patients may value high efficacy (e.g.,highly effective pain relief) more than low power consumption. Suchpatients will accordingly be willing to recharge their implanted devicesmore frequently in order to obtain better pain relief. Other patients,on the other hand, may be willing to tolerate an increase (e.g., aslight increase) in pain in order to reduce the frequency with whichthey recharge their implanted devices. Process portion 207 can includeaccounting for (e.g., weighting) patient-specific preferences in orderto identify one or more therapy signals or sets of therapy signaldelivery parameters that satisfy the patient's requirements.

FIG. 3 is a detailed flow diagram illustrating a representative process300 for selecting signal delivery parameters in accordance with anotherembodiment of the present technology. In a particular aspect of theillustrated embodiment, it is assumed or determined that otherstimulation parameters (such as pulse width and the locations of activecontacts, but excluding amplitude) are fixed, e.g., because they providereasonable efficacy for the patient. The process 300 can includeselecting a starting frequency (process portion 301), and selecting afrequency increment or list of frequencies (process portion 303). Forexample, process portion 301 can include selecting 10 kHz as a startingfrequency and process portion 303 can include selecting a list offrequencies that includes 10 kHz and 1.5 kHz. In this simple example,just these two frequencies will be tested, at a variety of signaldelivery amplitudes. In other cases, the list of frequencies can includemore values (e.g., 10 kHz, 5 kHz, and 1.5 kHz). In still furtherembodiments, a frequency increment can be used, e.g., in lieu of a listof frequencies. For example, the frequency increment can be 1 kHz, sothat multiple frequencies, spaced apart from each other by the 1 kHzincrement, can be tested over the course of the process. Accordingly,the process can allow the practitioner, manufacturer, and/or otherprofessional to select the number of frequencies tested, the values ofthe frequencies, and the manner in which the frequencies are selected indifferent ways for different patients.

In process portion 305, the process 300 includes selecting an amplitudeincrement. The amplitude increment can be selected to allow the processto cover a suitably wide range of amplitudes within a reasonable periodof time. It has been observed that the efficacy of particular highfrequency therapy signals may take some time to develop. This is unlikethe case for standard, low frequency SCS treatments, during which thepatient can immediately identify whether or not the paresthesiaassociated with a particular therapy signal masks or overlies the pain.Instead, the effects of high frequency signals, or changes in highfrequency signals, may take several hours to a day or so for the patientto detect. Accordingly, the amplitude increment can be selected by thepractitioner to allow a reasonable number of different amplitudes to betested over a reasonable period of time. For example, the practitionercan set the increment to be 0.1 mA in a particular embodiment so as tocover five different amplitudes over a period of five days, assuming theamplitude is incremented once every day. In other embodiments, thepractitioner can select other suitable values, e.g., ranging from about0.1 mA to about 2 mA, and ranging from about 0.5 days to about 5 days,with a representative value of from 1-2 days.

At process portion 307, the starting amplitude is selected. The startingamplitude will typically be selected to be at a value that produceseffective therapy. In process portion 309, the therapy is applied to thepatient at the starting frequency and starting amplitude. Processportion 311 includes receiving a response or efficacy measure from thepatient. The response can include the patient providing a pain score inaccordance with any of the scales or measures described above. Thepatient can provide this pain score via the patient remote 106 (FIG. 1A)so that the value is automatically stored, e.g., at the patient remote,or at the patient's implanted pulse generator. Process portion 313includes determining the expected energy consumption associated with thecombination of frequency and amplitude applied to the patient. Thisprocess can be executed by the patient remote 106 or otherpatient-controllable device, or by the implanted pulse generator (IPG)101, or by another device. In particular embodiments, the process ofdetermining the expected energy consumption need not be conducted in thesequence shown in FIG. 3. Instead, it can be conducted after or beforeall the planned combinations of amplitude and frequency have beentested. In particular, a more accurate estimate of the energyconsumption may include the actual time the patient uses each frequencyand amplitude pair. In any of these embodiments, the energy consumptioncan be expressed in a variety of suitable manners, including energy perunit time (e.g., power).

Process portion 315 includes determining whether the efficacy, asindicated by the patient, has decreased by greater than a thresholdamount relative to the baseline efficacy present at process portion 301.The threshold amount can be selected by the patient and/or practitioner.For example, the threshold can be selected to be a 10%, 20%, 30%, 40% orother decrease from an initial or baseline efficacy value. If this isthe first tested amplitude at the selected frequency, this step can beskipped. If not, and it is determined that the efficacy has notdecreased by greater than a threshold amount, then the amplitude isincremented, as indicated at process portion 317, and the steps ofapplying the therapy to the patient, receiving the patient's responseand determining the expected energy consumption are repeated. If theefficacy has decreased by greater than the threshold amount, then theprocess moves to process portion 319. Accordingly, the range withinwhich the amplitude is increased is controlled by the threshold value.This range can also be governed or controlled by other limits. Forexample, the IPG can have manufacturer-set or practitioner-set limits onthe amount by which the amplitude can be changed, and these limits canoverride amplitude values that might be within the efficacy thresholdsdescribed above. In addition, the patient can always override any activeprogram by decreasing the amplitude or shutting the IPG down, via thepatient remote 106 (FIG. 1A).

After it has been determined that the efficacy has decreased by at leastthe threshold amount, the amplitude is decreased at process portion 319.In a particular embodiment, the amplitude can be decreased back to thestarting amplitude set in process portion 307, and the amplitude tests(with decreasing amplitude) can continue from that point. In anotherembodiment, if it is desired to re-test amplitudes that have alreadybeen tested in process portions 309-315, those amplitudes can bere-tested as the amplitude is decremented from the value that resultedin the efficacy threshold being met or exceeded.

In process 321, the therapy is applied to the patient at the decreasedamplitude and the process of testing the therapeutic efficacy atmultiple amplitudes is reiterated in a manner generally similar to thatdescribed above with reference to incrementing the amplitude. Inparticular, process portions 323 (receiving a response and/or efficacymeasure from the patient), and process portion 325 (determining theexpected energy consumption associated with the decreased amplitude) arerepeated as the amplitude is decreased. In process portion 327, theprocess includes determining whether the efficacy has decreased bygreater than a threshold amount. This threshold amount can be the sameas or different than the threshold amount used in process portion 315.If it has not decreased by more than the threshold amount, the loop ofdecreasing amplitude (process portion 329), applying the signal to thepatient, and testing the result is repeated until it does.

In process portion 331, the process includes determining whether allfrequencies to be tested have in fact been tested. If not, in processportion 333, the frequency is changed and the process of incrementingand then decrementing the amplitude is repeated at the new frequency. Ifall frequencies have been tested, then process 335 includes selectingthe signal or signals having or approximating a target combination ofefficacy and energy consumption.

In a simple case, for example, if the practitioner tests 10 kHz and 1.5kHz at a variety of amplitudes, process portion 335 can also be fairlysimple. For example, process portion 335 can include determining if thelowest amplitude that produces effective therapy at 10 kHz also produceseffective therapy at 1.5 kHz. If it does, then clearly the energyconsumption at 1.5 kHz will be less than the energy consumption at 10kHz, at the same amplitude. Accordingly, process portion 335 can includeselecting the frequency to be 1.5 kHz for delivering additional signalsto the patient. Furthermore, if it is clear that all tested amplitudesat 1.5 kHz will consume less energy than even the lowest amplitude at 10kHz, then process portion 335 can include determining whether any of theamplitudes at 1.5 kHz produce effective pain relief. If any do, theprocess can include selecting the lowest amplitude that does so.

In other embodiments, process portion 335 can include a more involvedprocess of pairing pain scores and energy consumption levels for each ofthe tested combinations and automatically or manually selecting the pairthat produces the expected best efficacy at the expected lowest energyconsumption. The energy consumption can be calculated, expressed, and/orotherwise described as a total amount of energy over a period of time,an energy rate (power) and/or other suitable values. The selectionprocess will include weighting pain reduction and energy consumption inaccordance with any preferences, e.g., patient-specific preferences.Accordingly, the patient may prefer a less-than-optimum pain score, butimproved power consumption, or vice versa. In any of these embodiments,the selected signal is then applied to the patient in process portion337, e.g., to provide a course of therapy. The foregoing process can berepeated if desired, for example, if the patient's condition changesover the course of time.

One feature of the foregoing embodiments is that the manufacturer orpractitioner can select the range of amplitudes over which the foregoingtests are conducted to be well higher than the point at whichtherapeutic efficacy is expected to decrease significantly, yet belowthe point at which the patient is expected to experience anyuncomfortable or undesirable side effects. For example, in a particularembodiment, the patient is expected to receive effective therapeuticresults at an amplitude range of from about 2 mA to about 6 mA. Theoverall amplitude test range can be selected to be between about 0 mAand about 10 mA or another suitable value that is not expected toproduce undesirable side effects. As a result, the system canautomatically test a suitable number of amplitude values and frequencyvalues, without placing the patient in any discomfort. As a furtherresult, the system can automatically test the foregoing amplitude andfrequency values in an autonomous manner, without requiring practitioneror patient action, beyond the patient recording pain scores or otherresponses as the parameters change. Accordingly, the process foridentifying an effective, low power consumption therapy signal can bemore fully automated than existing processes and can accordingly beeasier, less time-consuming, and/or less expensive to perform.

From the foregoing, it will be appreciated that specific embodiments ofthe presently-disclosed technology have been described herein forpurposes of illustration, but that various modifications may be madewithout deviating from the disclosed technology. For example, severalembodiments were described above in the context of variations in theamplitude and frequency of the signal, in order to determine aneffective yet low-power therapy signal. In other embodiments, theprocess can include other parameters that are also varied to determinelow-power effective therapy signals, in combination with amplitude andfrequency, or in lieu of amplitude and frequency. Suitable signalparameters include pulse width, inter-pulse interval, and duty cycle.

Other embodiments of the present technology can include furthervariations. For example, instead of selecting an amplitude increment, asdiscussed above with reference to FIG. 3, a list of amplitude values canbe used to increment and/or decrement from a starting amplitude value.The patient can receive a prompt (e.g., via the patient remote) when thesystem requires an input, such as a pain score. Instead of varying theamplitude at a constant frequency, the system can vary the frequency ata constant amplitude. Instead of first increasing amplitude and thendecreasing amplitude, these processes can be reversed. In anotherembodiment the amplitude can be changed in only one direction, e.g., bystarting at zero amplitude or starting at the top of the amplitude testrange.

As discussed above, many of the steps for carrying out the foregoingprocesses are performed automatically, without continual involvement bythe patient and/or practitioner. The instructions for carrying out thesesteps may be carried on any suitable computer-readable medium or media,and the medium or media may be distributed over one or more components.For example, certain steps may be carried out by instructions carried bythe IPG, the patient remote and/or the physician's programmer, dependingon the embodiment. Accordingly, a portion of the instructions may becarried by one device (e.g., instructions for receiving patientresponses may be carried by the patient remote), and another portion ofthe instructions may be carried by another device (e.g., theinstructions for incrementing and decrementing the amplitude may becarried by the IPG).

Certain aspects of the technology described in the context of particularembodiments may be combined or eliminated in other embodiments. Forexample, in some embodiments, the foregoing process can include onlyincrementing the amplitude or only decrementing the amplitude, ratherthan both, as discussed above. In other embodiments, certain steps ofthe overall process can be re-ordered. For example, the expected energyconsumption value can be determined before or after receiving a responsefrom the patient, and/or can be performed on a list of amplitude valuesall at one time. In some embodiments, certain amplitude/response pairsmay be eliminated from consideration or from further calculations, e.g.,if the data are determined to be defective, and/or for any othersuitable reason.

3.0 ADDITIONAL EMBODIMENTS

In one embodiment, there is provided a method for programming a spinalcord stimulation system for providing pain relief to a patient. Themethod comprises configuring a signal generator to deliver a firsttherapy signal at a first frequency, and a second therapy signal at asecond frequency different than the first. For both the first and secondsignals, the method includes carrying out the following processes: (i)increasing an amplitude of the signal, over multiple steps, from abaseline amplitude at which the patient has a baseline response; (ii)for individual step increases, determining the patient's response to theincreased amplitude; (iii) decreasing the amplitude over multiple steps;and (iv) for individual step decreases, determining the patient'sresponse to the decreased amplitude. The method can further includecomparing the patient responses to the first therapy signal with thepatient responses to the second therapy signal and, based on the patientresponses and an expected energy consumption for the first and secondtherapy signals, selecting one of the first and second therapy signalsfor additional therapy to the patient.

In particular embodiments, the first frequency can be in a frequencyrange from 10 kHz to 100 kHz, inclusive, and the second frequency can bein a frequency range from 1.5 kHz to 10 kHz. The process of increasingor decreasing the amplitude can be halted if the pain score worsens by athreshold value, and the threshold value can vary from 10% to 40%, inparticular embodiments.

Another representative embodiment of the technology is directed to aspinal cord stimulation system. The system comprises a signal generatorcoupleable to a signal delivery device to deliver electrical therapysignals to a patient at a first frequency and a second frequencydifferent than the first. The system can further include acomputer-readable medium programmed with instructions that, whenexecuted, for both the first and second signals: (i) increases anamplitude of the signal, over multiple steps, from a baseline amplitudeat which the patient has a baseline response; (ii) at individual stepincreases, receives the pain score based on the patient's response tothe increased amplitude; (iii) decreases the amplitude over multiplesteps; and (iv) for individual step decreases, receives the pain scorebased on the patient's response to the decreased amplitude. Theinstructions compare the pain scores corresponding to the first therapysignal with the pain scores corresponding to the second therapy signal.Based on the pain scores and an expected energy consumption for each ofthe first and second therapy signals, the instructions determine one ofthe first and second therapy signals for additional therapy to thepatient.

I claim:
 1. A method for configuring a spinal cord stimulation systemfor providing pain relief to a patient, wherein the spinal cordstimulation system includes a signal generator configured to generate anelectrical therapy signal, one or more computer-readable mediaconfigured to store therapy signal parameters, and a signal deliverydevice configured to receive the electrical therapy signal from thesignal generator and deliver the electrical therapy signal to thepatient's spinal cord region, the method comprising: (a) configuring thesignal generator to deliver a first therapy signal with a first set oftherapy signal parameters, wherein the first set of therapy signalparameters includes a first frequency in a frequency range from 10 kHzto 100 kHz, inclusive; (b) configuring the signal generator to deliver asecond therapy signal with a second set of therapy signal parameters,wherein the second set of therapy signal parameters includes a secondfrequency in a frequency range from 1.5 kHz to 10 kHz, (c) for both thefirst and second therapy signals, configuring the one or morecomputer-readable media to: (i) change a therapy signal parameter of thesignal, over multiple steps, from a baseline value at which the patienthas a baseline pain score, wherein the therapy signal parameter includesat least one of a signal amplitude, a signal pulse width, or a signalduty cycle; and (ii) configuring the one or more computer-readable mediato, for individual step changes, receive a patient pain scorecorresponding to the changed value; (d) configuring the one or morecomputer-readable media to compare the pain scores corresponding to thefirst therapy signal with the pain scores corresponding to the secondtherapy signal; and (e) configuring the one or more computer-readablemedia to select one of the first and second therapy signals foradditional therapy to the patient, based on the pain scores and anexpected energy consumption for the first and second therapy signals. 2.The method of claim 1, further comprising configuring the one or morecomputer-readable media to halt at least one of increasing or decreasingthe amplitude if the pain score worsens by at least a threshold value.3. The method of claim 2 wherein the threshold value is from 10% to 40%,inclusive, of the patient's baseline pain score.
 4. The method of claim2 wherein the threshold value is from 15% to 35%, inclusive, of thepatient's baseline pain score.
 5. The method of claim 2 wherein thethreshold value is from 10% to 20%, inclusive, of the patient's baselinepain score.
 6. The method of claim 2 wherein the threshold value isselected by the patient.
 7. The method of claim 1 wherein configuringthe one or more computer-readable media to select one of the first andsecond therapy signals includes configuring the one or morecomputer-readable media to select the second therapy signal if a painscore corresponding to the second therapy signal at a particularamplitude is the same as or better than a pain score corresponding tothe first therapy signal at the same particular amplitude.
 8. The methodof claim 1 wherein the pain score is selected from the group comprisinga VAS, NRS, or Likert score.
 9. The method of claim 1, furthercomprising configuring the one or more computer-readable media todetermine the expected energy consumption for the first and secondtherapy signals.
 10. The method of claim 1 wherein configuring the oneor more computer-readable media to select one of the first and secondtherapy signals for additional therapy includes configuring the one ormore computer-readable media to select based at least in part on apatient preference for at least one of a pain reduction level or acharging interval.
 11. A method for programming a spinal cordstimulation system for providing pain relief to a patient, the methodcomprising: (a) configuring a signal generator to deliver a firsttherapy signal at a first frequency; (b) configuring the signalgenerator to deliver a second therapy signal at a second frequencydifferent than the first, (c) configuring one or more computer-readablemedia to, for both the first and second therapy signals: (i) change asignal delivery parameter of the therapy signal, over multiple steps,from a baseline value at which the patient has a baseline response; and(ii) for individual step changes, determine the patient's response tothe changed value; (d) configuring the one or more computer-readablemedia to compare patient responses to the first therapy signal with thepatient responses to the second therapy signal; wherein the patientresponses include at least one of a pain score or a value correlatedwith the patient's pain level; and (e) configuring the one or morecomputer-readable media to select one of the first and second therapysignals for additional therapy to the patient, based on the patientresponses and an expected energy consumption for the first and secondtherapy signals.
 12. The method of claim 11 wherein the second frequencyis lower than the first frequency.
 13. The method of claim 12, furthercomprising configuring the one or more computer-readable media to selectthe second therapy signal if a patient response to the second therapysignal at a particular amplitude is the same as or better than a patientresponse to the first therapy signal at the same particular amplitude.14. The method of claim 11 wherein configuring the one or morecomputer-readable media to select includes configuring the one or morecomputer-readable media to select a combination of amplitude andfrequency that produces a less than optimum pain score to obtain lowerenergy consumption.
 15. The method of claim 11 wherein configuring theone or more computer-readable media to select includes configuring theone or more computer-readable media to select a combination of amplitudeand frequency that produces less than optimum energy consumption toobtain a lower pain score.
 16. The method of claim 11 whereinconfiguring the one or more computer-readable media to select includesconfiguring the one or more computer-readable media to select acombination of amplitude and frequency that produces the lowest energyconsumption and lowest pain score obtained as a result of changing theamplitude at the first and second frequencies.
 17. The method of claim11, further comprising configuring the one or more computer-readablemedia to determine the expected energy consumption for the first andsecond therapy signals.
 18. The method of claim 11 wherein configuringthe one or more computer-readable media to select one of the first andsecond therapy signals for additional therapy includes configuring theone or more computer-readable media to select based at least in part ona patient preference for at least one of a pain reduction level or acharging interval.
 19. A spinal cord stimulation system, comprising: asignal generator coupleable to a signal delivery device to deliverelectrical therapy signals to a patient at a first frequency and asecond frequency different than the first; and one or morenon-transitory computer readable media programmed with instructionsthat, when executed: for both the first and second therapy signals,change a signal parameter of the signal, over multiple steps, from abaseline value at which the patient has a baseline response, wherein thesignal parameter includes at least one of a signal amplitude, a signalpulse width, or a signal duty cycle; and (ii) for individual stepchanges, receive a pain score based on the patient's response to thechanged value; compare the pain scores corresponding to the firsttherapy signal to the pain scores corresponding to the second therapysignal; based on the pain scores and an expected energy consumption foreach of the first and second therapy signals, select one of the firstand second therapy signals for additional therapy to the patient; anddirect the therapy signal to the patient.
 20. The system of claim 19wherein the signal generator is an implantable signal generator.
 21. Thesystem of claim 20 wherein the one or more computer-readable media iscarried by the implantable signal generator.
 22. The system of claim 20wherein a first portion of the one or more computer-readable media iscarried by the implantable signal generator and a second portion of theone or more computer-readable media is carried off the implantablesignal generator.
 23. The system of claim 20 wherein a first portion ofthe instructions are executed by the implantable signal generator and asecond portion of the instructions are carried out by a patient remote.24. The system of claim 19 wherein the signal parameter is a signalamplitude and wherein an incremental value for changing the amplitude is0.1 mA.
 25. The system of claim 19 wherein the first frequency is higherthan the second frequency.
 26. The system of claim 19 wherein the firstand second frequencies are both at least 1.5 kHz.
 27. The system ofclaim 19 wherein the first frequency is from 10 kHz to 100 kHz,inclusive and the second frequency is from 1.5 kHz to 10 kHz.
 28. Thesystem of claim 19 wherein the instructions, when executed, determinethe expected energy consumption for the first and second therapysignals.
 29. The system of claim 19 wherein the instructions, whenexecuted, select one of the first and second therapy signals foradditional therapy based at least in part on a patient preference for atleast one of a pain reduction level or a charging interval.